I think part of the problem is that at endgame GT7 is functionally worse than something like AC.
At endgame in both you're going to be making your own fun and driving what you feel like. But GT7 locks all the cars behind a credit grind, making it hard to set up races exactly how you want. AC just gives you the cars and lets you have fun.
In the past the tradeoff would have been that Gran Turismo had a massive single player component, and the restricted car ownership would have been in service of that mode of gameplay. That's just not there in GT7, it dies of crib death after the menus and a handful of random events.
The way GT7 allows you to play at endgame, games like AC and PC2 do better. They allow you the freedom to make your own fun in a way that GT7 doesn't, since none of the games offer that much in the way of an endgame single player experience.
Unless you want someone to take all your toys away and make you work to get them back, then GT7 is for you. Some people are into that, but most wouldn't call it fun. I buy racing games to race the cars, not to drive a car I don't like to maybe one day earn access to a car I do.
For the people who will misrepresent this argument, I don't think GT7 should unlock all the cars (well, they should have a fully unlocked arcade mode but that's another thing). I think they should have a decent amount of single player content with a reasonably balanced economy because that's why GT does best. I just think that in failing to do so they've driven players into a mode of play that more resembles the "traditional" sims where everything is unlocked, but does it worse.